var changeFont = function () {
  var nWdWidth = window.innerWidth;
  var nFontSize = nWdWidth / 750 * 100;
  document.getElementsByTagName("html")[0].style.fontSize = nFontSize + "px";
}
changeFont();
var changeHeight = function () {
  var oWrap = document.querySelector("#app");
  var wdH = window.innerHeight;
  if (wdH > oWrap.offsetHeight) {
      oWrap.style.minHeight = wdH + "px";
      oWrap.style.minHeight = "initial";
  }
}
window.onresize = function () {
  changeFont();
}